It is the goal of this project to increase our understanding of several unsolved problems in the field of the synthesis and regulation of proteins. Our focus of interest during the past year was two-fold. Firstly, we continued our examination of the nature of the regulation of the synthesis of transfer ribonucleic acid in Escherichia coli. Secondly, we further pursued our efforts to understand the mechanism of the reaction catalyzed by the enzyme from Escherichia coli that attaches arginine to transfer ribonucleic acid.